ATS Criteria for Acceptable Spirometry

Acceptable flow-volume loop includes:

• Satisfactory start-of-test
• Minimum 6-second exhalation
• End-of-test criteria
• < 30 mL change for at least 1 s after 6-second exhalation
• Subject unable to continue or is unsafe to continue
• Obvious plateau

Acceptable flow-volume loop must not have:

• Unsatisfactory start of exhalation (Extrapolated volume < 5% of FVC or 150 mL)
• Cough during first second
• Early termination of exhalation
• Valsalva maneuver or hesitation that causes cessation of airflow
• Leak
• Obstructed mouthpiece

Reproducibility:

• FVC: Next largest and largest must be within 200 mL
• FEV1: Next largest and largest must be within 200 mL

Bronchodilator change:

• 200 mL AND 12% improvement FEV1 and/or FVC
  • Note that the upper limit of normal for short acting bronchodilator change in a population of healthy children and adults is 6-9%

Obstruction Definitions

A fixed percentage below the predicted FEV1/FVC	For example, 5% or more below the predicted FEV1/FVC; if the predicted FEV1/FVC is 72%, a value of 67% would be considered abnormal
Below relatively arbitrary aged-based norms (NAEPP EPR3)	“normal” FEV1/FVC for a person 8-19 yo: ≥85% 20-39 yo: ≥80% 40-59 yo: ≥75% 60-80 yo: ≥70%
Global Initiative for Chronic Obstructive Lung Disease consortium	An FEV1/FVC <70% after administration of a short-acting bronchodilator (e.g., 4 puffs of albuterol through a spacer)
ATS/European Respiratory Society Task Force on the Standardisation of Lung Function Testing	An FEV1/FVC (or FEV1-to-VC ratio) less than the lower limits of normal defined as less than the fifth percentile predicted

Bronchodilator Reversibility Definitions

• Note that the upper limit of normal for short acting bronchodilator change in a population of healthy children and adults is 6-9%

FEV1 Severity

Degree of Severity-------	FEV1 %predicted-------
Mild	>70
Moderate	60-69
Moderate-severe	50-59
Severe	35-49
Very severe	<35

COPD Staging (GOLD)

Stage	FEV1/FVC-------	FEV1 %predicted
I - Mild	<0.70	≥80
II - Moderate	<0.70	≥50-80
III - Severe	<0.70	≥30-50
IV - Very severe-------	<0.70	<30 or <50 plus chronic respiratory failure-------

CDC Spirometry Reference Value Calculator

Classic Flow Volume Curves

References